Various types of endoscopes are known in the art for visual inspection and diagnosis of the rectum and sigmoid of the large intestine. Rigid rectoscopes and sigmoidoscopes are most commonly used for this purpose, since they are durable, easy to use and relatively inexpensive.
To perform an examination using the rigid rectoscope (or sigmoidoscope), the physician first inserts a speculum through the anus. An obturator, having a blunt, rounded distal end, is fitted inside the speculum and protrudes distally therefrom to ease the insertion. Once the speculum is in place, the physician withdraws the obturator and closes the proximal end of the speculum with a plug. A special telescope is fitted into the plug, which enables the physician to view the inside of the rectum and sigmoid at the distal end of the speculum, either by direct vision or using a video camera coupled proximally to the telescope. In order to illuminate the area under view, a light source in an external console is coupled proximally to the speculum by fiberoptics. Typically, the plug also includes one or more working channels, which are used for irrigation, insufflation or insertion of surgical tools through the speculum.
Various rectoscopes and sigmoidoscopes of this type are available commercially. For example, Karl Storz GmbH, of Tuttlingen, Germany, offers the model 24911S rectoscope, which may be used with a rod lens telescope (for example, model 24946B) to view the rectum either under direct view or using a Karl Storz Endovision video camera. The rectoscope and accessories are made from stainless steel to allow disinfection and autoclaving between uses.
Rectoscopes and sigmoidoscopes having a disposable speculum and obturator are also available, such as the KleenSpec disposable sigmoidoscope produced by Welch Allyn Inc., of Skaneateles Falls, N.Y. The speculum and obturator are made of plastic. The speculum clips or screws onto a multi-use handle, to which a light source, telescope, video camera and instruments may be attached.
Flexible sigmoidoscopes and colonoscopes are also known in the art. Most such scopes include a fiberoptic bundle for conveying images from their distal end, within the intestine, to an eyepiece or video camera fixed to the proximal end. Some such scopes, such as the Pentax ES-3801 PVE Video Sigmoidoscope, made by Asahi Optical Company of Tokyo, have a CCD detector with an objective lens at its distal end. By comparison with rigid rectoscopes and sigmoidoscopes, however, flexible scopes are costly, fragile and difficult to clean.